FR2903478A1 - METHOD FOR HEATING A CHARGE, IN PARTICULAR ALUMINUM - Google Patents

Abstract

The invention relates to a method for heating a charge with a flame generated by a lance and / or a burner, characterized in that in a first phase, the flame is directed towards the charge and in a second phase, the flame is directed substantially parallel to the load.

Description

The present invention relates to a method of heating a charge to

  using a flame generated by a lance and / or a burner and in particular a lance and / or an adjustable-flame burner comprising at least one injection channel of at least one main jet of oxidant and / or fuel and / or an oxidizing and combustible premix. The vast majority of industrial furnaces or boilers use burners that operate in non-premixed combustion mode, that is to say in which the oxidant and the fuel arriving separately to the combustion site. The mixture of the fuel and the oxidant is then made, in part (use of a quarry block or prechamber) or in full, inside the combustion chamber. This mixture is controlled by the design and operating parameters of the burner, and determines the performance of the burner (operating range, heat transfer to the load to be heated and / or emission of pollutants). In practice, the burner design determines the interaction conditions of the different jets or flows of oxidant and fuel used by the burner. Once the burner is completed, only the operating conditions can be modified. This is also true for the so-called premix burners in which the oxidant / fuel mixture is produced upstream of the injection into the burner consisting of a single injection tube. The operating conditions of industrial processes can change over time. This is by nature the case of intermittent processes but it is also the case of continuous processes for which the characteristics of the charges to be heated can vary according to the production needs. This is more generally the case for any production unit subjected to aging or sensitive to the variable conditions of their environment.

  To adapt the performance of the burners to variable operating conditions, the operator usually has only two parameters: the burner operating power and the level of excess oxidant (oxygen surstoichiometry). Some combustion technologies, however, allow discrete modes of operation. This is for example the case of so-called dual-pulse burners that use two different injection systems depending on whether one wants to operate the burner at low or high impulse. These two modes of operation make it possible to increase the range of operation or use of the burner. However, modifications of the point and / or the operating mode are most often insufficient to optimize under all conditions the performance of the burners or processes using these burners. For example, the cyclic introduction into a solid-temperature melting furnace at ambient temperature will cause the operator (or control system) to increase the heating power so as to obtain the fastest possible melting (in view of to increase productivity), but without degrading the melt load (product quality) or overheating the oven (service life of the equipment). This compromise between productivity and quality and / or life depends in particular on the ability of the system to transfer energy to the load, avoiding local overheating thereof or furnace refractories. This compromise results in a melting time below which any productivity gain will be counterbalanced by a degradation of the quality of the product or the reduction of the life of the oven. It is known from WO-A-9744618 a burner having a central jet of fuel surrounded by a plurality of jets of secondary oxidants, themselves surrounded by a plurality of tertiary jets of the same oxidant. By removing a greater or lesser portion of the secondary oxidant on the tertiary oxidant, there follows a variation of the position and the shape of the flame, related to the decrease in the flow of a jet correspondingly compensated by the increased flow of another jet (secondary and tertiary jets). It is thus possible in operation to modify the position of the flame relative to the load and thus increase or reduce the heat transfer without modifying the power of the burner. However, the maximum deflection of the flame is limited to about 15 from the middle position to the extreme position (at most 30 in total), not allowing the incident flame to scan a large surface of the load, and the construction The corresponding burner is relatively heavy because three orifices are required to bend the position of the flame in a direction (fuel in the center, oxidant at the ends). In addition, the properties of the flame change according to its position since the properties of the mixture vary with the angle of incidence (mixture external to the burner block), which induces a variation of the pollutant emissions, the quality of the transfer. radiative (flame brightness) and flame length (heat release peak position). The invention proposes to control the heating of a load without causing local overheating and overheating in the time. According to the invention, the heating of the charge is characterized in that in a first phase, the flame is directed towards the charge and in a second phase, the flame is directed substantially parallel to the charge. Preferably, the lance and / or the burner will be fixed, which requires to move the flame by means other than mechanical. For example, during the first phase, the injection angle of the flame is between about 90 and 5 and in the second phase the injection angle of the flame is between about 5 and 0. Preferably, the injection angle of the flame during the first phase is between 5 and 75, preferably 25 and 45. According to one variant, the flame is of direction and / or of variable opening. More particularly, the flame is created by at least one jet resulting in direction and / or variable opening, said jet resulting from the interaction between at least one main fluid jet and at least one secondary fluid jet. Preferably, the ratio of the flow rates of at least one main jet and at least one secondary jet which interact with each other is varied, while, more preferably, the change of direction and / or Opening of the flame results from the only interaction of at least one main jet and at least one secondary jet. According to a variant of the invention applicable to combustion, a burner and a method of use thereof are made capable of permitting a modification of the thermal resistance between the flame and the load in operation and in a continuous manner, of to increase the heat transfer to the load, without adding energy to the furnace, and without degrading the quality of the melted filler, increasing productivity without reducing the life of the furnace. The invention also proposes controlling a main fluid jet by the interaction with another jet (said jet actuator), the interaction between the two jets preferably occurring inside the means delivering this main jet ( tube, quarlet, etc ...) before said main jet opens out of said means, or possibly where the main jet leads from these means or near this place. The burner according to the invention is characterized in that it comprises means for injecting at least one secondary fluid jet (2) opening into or close to said channel (3) and in that the injection axis of said secondary fluid jet (2) makes an angle> 0 with the injection axis of the main jet. It may also include means for controlling the momentum of at least one main jet and / or at least one secondary jet. It may also preferably comprise interaction means for interacting at least one main fluid jet and at least one secondary fluid jet and generating a jet of fluid resulting from this interaction whose direction and / or opening (and in a more general way the form) are variable. According to a first variant, the burner comprises a quarl (for example ceramic) disposed at the end of said injection channel, means for injecting at least one secondary fluid jet comprising at least one injection channel of said fluid at least partially disposed within the quarl. According to another variant, the burner comprises at least one oxidant injection channel and at least one fuel injection channel, arranged concentrically, one parallel to the other. According to another variant, the burner comprises at least one oxidant injection channel and at least one fuel injection channel, arranged independently of one another and preferably parallel to one another. According to another variant, the burner is characterized in that the channel 20 for injecting at least one main jet comprises at least a first portion disposed in a block of material, said first part opening on at least a first opening located on one of the faces or surfaces of the block. According to a preferred variant of the invention, the burner is characterized in that the injection channel of at least one main jet comprises at least a second part consisting of a first tube, of any section, through which at least one of said main streams flows. According to another variant, the burner is characterized in that the means 30 for injecting at least one secondary fluid jet comprise at least a third pipe portion in said block of material, said pipe opening on at least a second opening . According to another variant, the burner is characterized in that at least one of the second openings opens on one of the faces of the block of material, preferably on the face or surface on which at least one opens. first 5 openings, more preferably near it. According to a preferred variant of the invention, at least one of the second openings opens on at least one of the first pipe portions. In general, the angle between the direction of at least one main jet and the direction of at least one secondary jet, in the direction of flow of these jets, is less than or equal to 90, when their intersection. Also preferably, the distance (L in FIG. 1) between at least one of the first openings and at least one of the second openings is less than or equal to ten times the square root of the outlet section of the smaller first openings (L 10 I s), preferably less than or equal to five times, more preferably three times this section. The invention also relates to a method for dynamically or actively controlling the performance of a system for injecting fluids or combustion systems. The interaction is preferably carried out by means of secondary jets (also called actuator jets), impinging on the primary jets in order to modify the flow of the primary and secondary jets and produce a resulting jet whose direction and / or The opening can be modified according to the characteristics (in particular direction and momentum) of the primary and / or secondary jets. This method can be used to regulate in closed loop or open loop the performance of a combustion system or more generally of industrial processes implementing injections of fluid jets (liquid, gaseous or solid dispersion). Thus, the method according to the invention is a method for injecting at least one resulting fluid jet, characterized in that it consists in: injecting at least one main fluid jet, injecting at least one jet secondary fluid, 5 - causing at least one main fluid jet to interact with at least one secondary fluid jet so as to generate at least one jet resulting from this interaction, said interaction making it possible to vary the direction and / or the opening of said resultant jet. Preferably, the number of secondary jets interacting with a main jet to achieve the desired effect on the resulting jet will be minimized so as to reduce the cost of manufacturing the injector but also the cost of the power and control system. flow rates of the fluids if one wants to control the actuator jets independently. A mono-directional effect will be obtained preferably with a single actuator, the rotational effect with 4 actuator jets or less if one wants to favor certain directional effects. (The direction of a jet is defined as a unit vector normal to the flow passage section oriented in the direction of flow, that is, from upstream to downstream). To modify the direction of a resulting jet, it will be ensured that for at least one main jet / secondary jet interaction, the axes of the corresponding flows are coplanar and that in the plane defined by the center of inertia of the common surface the two flows and the directions of the two flows, the latter forming an angle of between about 10 and 90. Preferably, one will choose an incidence of about 90 of the secondary jet on the main jet. In order to obtain this effect in practice, it will be preferable when the auxiliary jet flows through a pipe that it has a direction substantially perpendicular to that of the pipe of the main jet, over a length f which will preferably be between 0.5 and 5 times the thickness e (dimension in the direction of flow of the main fluid) of said pipe (e is the diameter of the pipe when it is cylindrical). Of course, it is also possible that this length f is greater than 5e, but this does not then bring any additional effect of impact of the secondary jet on the primary jet. For example, for a burner with a CXHy fuel injection and an oxidant injection, at least f = 5 mm for a burner of 100 KW and f = 50 mm for a burner of 10 MW. According to a variant of the invention, to rotate a resulting jet (and thus change its opening), it will be ensured, preferably, that at the location (center of inertia of the common surface to the two flows) where the main jet and at least one secondary jet interact, on the one hand, the axis of the secondary jet belongs to the plane P perpendicular in this place to the main direction, and on the other hand, the angle between the direction the secondary jet and the tangent to the common surface of the two flows in this plane is between 0 and 90, preferably between 0 and 45. To obtain both a directional and a rotational effect, the teaching of the preceding paragraphs will be combined. For dynamic variation of the directional and rotational effects, it is possible, for example, to provide a plurality of secondary jet injection systems, for example progressively offset from the axis of the main jet towards its periphery. The axial secondary jet will allow only a change of direction of the flame, a secondary jet impacting the main jet near its periphery allowing almost only an opening of the jet, while an injection between the two will allow a combination of the two effects . By providing separate channels with secondary jet supply valves, it is thus possible to change the shape and direction of the main jet by simply actuating said valves. The distance L between the output section of an actuator jet and the outlet section 30 of the main jet of the injector makes it possible to control the impact of the actuator jets on the main jet. For example to maximize the directional effect, we will try to minimize this distance. In contrast, if it is desired to develop vortex structures in the main jet so as to increase the opening of the resulting jet, this distance L will be increased. However, this distance will remain within the limits defined above. According to another variant of the invention, the means for controlling the effect of the actuator jets on the main jet will be constituted by means for controlling the ratio of the pulses of the jets. This ratio is a function of the ratio of the main jet sections and the actuator jets, the ratio of the flows in the actuators to the total flow of the resulting jet and the ratio of the densities of the fluids in the main jet and in the actuators. (In the following paragraphs, when considering the variation of one of these ratios, the other two are considered constant.) The greater the ratio value of the main jet section and the section of each secondary jet increases, the more the corresponding actuator jet has a significant impact on the main jet. Also, a ratio of sections between 5 and 50, more preferably between 15 and 30, will preferably be chosen. The ratio of the flow rate of all the actuator jets to the total flow rate of the resulting jet will vary between 0 and 0.5 and preferably between 0 and 0.3, more preferably between 0 and 0.15, knowing that the higher this ratio of flow rates, the greater the deviation of the jet will be important. The ratio of the density of each fluid constituting the actuator jets to the fluid density of the main jet makes it possible to control the impact of these jets on the main jet. The lower the value of this ratio, the greater the effect of the actuator jet on the main jet. The same fluid will most often be used in the actuator jets and in the main jet (ratio equal to unity). To increase (at constant mass flow) the effects of the actuator jets a fluid of lower density than that of the fluid in the main jet will be used. The nature of the fluid in the actuator jets will be chosen according to the intended application. For example, to control the deflection of an air jet, a mixture of air and helium (of lower density) may be used or to increase the entrainment of combustion products in a flame whose fuel is propane, control the main jet of fuel and / or oxidizer with a secondary jet of water vapor. In general, the ratio of densities (or densities) of the densest fluid to the least dense fluid may vary between 1 and 20, preferably between 1 and 10, more preferably between 1 and 5. From In a general manner also, the geometry of the injection section of the main and / or secondary jets may be of any shape and in particular circular, square, rectangular, triangular, oblong, multi-lobes, etc. The geometry of these Injection sections influence the development of the resulting jet instabilities. For example, a jet output of a triangular shaped injector will be more unstable than that from a circular injector, this instability favoring the mixing of the resulting jet with the surrounding medium. Similarly an oblong injector will favor in a field near the injector the non-symmetrical development of the jet unlike a circular or square shaped injector. With respect to the physicochemical properties of the fluid used to make the actuator jets, they may be chosen to control certain properties of the resulting flow. For example, the reactivity of a mixture of main jet fuel (eg, natural gas), oxidizer (eg air) by use of oxygen (or other oxidant), and / or hydrogen may be modified. (or other fuel). Among the terms used in the present description, some deserve to be more precisely defined within the scope of the invention in order to better delimit their scope. Thus, the term thickness (e) means in fact the dimension of the pipe 4 in the direction of flow of the fluid 3 (according to the arrow) on the face of FIG. 1. In the particular case of this FIG. the diameter of the pipe 4 since it is cylindrical in this example. The term "jet opening" generally denotes, for a jet emerging from a cylindrical duct such as 7 in FIG. 1, the angle between the longitudinal axis of symmetry of the duct and the generatrix at the surface of the jet which is inclined by about 15 relative to this axis, in the absence of interaction with another jet up to an inclination of up to 70 and more (see Figure 9a). By extension, the term "opening" will designate the shape of the jet coming from a pipe when it does not have a circular section, the jet fluid deviating from the axis of the pipe. The invention also relates to a method for heating a charge with the aid of a tool generating a flame such as a burner or a lance described in the present application, in which the pulse ratio is modified, if necessary, on the one hand. the oxidizer jet and / or fuel and / or premix and secondly the secondary fluid jet, so as to vary the direction (and / or opening) of the flame relative to the load. According to an alternative embodiment, the method is characterized in that the fuel flow rate is zero. In this particular case, this means that the tool that generates a flame is a lance (to inject an oxidant such as oxygen, for example) whose jet to a direction and / or a variable opening. Of course, the same lance may be used to inject fuel, liquid and / or gaseous and / or solid, for example a pulverized coal lance (gas such as air that propels solid powder such as coal). . If we equip the end of the lance, just before the interaction of the main and secondary jets, with a nozzle having a convergent / divergent (also called Laval nozzle in the literature), we can at the exit of the divergent obtain (in a manner known per se in the literature) a jet of supersonic main fluid, for example a supersonic oxygen jet which can then be of variable direction (possibly of variable opening but generally losing its supersonic speed, which allows alternate subsonic and supersonic speeds in some processes). It is possible to act on the main jet with the aid of the secondary jet preferably only when the speed of the jet of fluid at the outlet of the Laval nozzle is only subsonic (by reducing the pressure upstream of the nozzle of Laval). This can allow in a subsonic injection phase to scan the entire load by acting on the main jet as described in the present application, then in a supersonic phase to act more limited or even zero ( low amount of movement of the secondary jet to the same amount of motion zero) on the supersonic main jet (application in metallurgy on a converter, electric furnace, etc ...). According to another variant, the method is characterized in that at least two auxiliary jets are used, so as to obtain a variation of the direction of the flame in at least two secant planes in order to scan at least a part of the load surface. According to another variant, the method is characterized in that the axis of the main and secondary jets are not intersecting. According to another variant, the method is characterized in that means are provided for controlling the momentum of at least one main jet and / or at least one secondary jet. Of course, the action of a secondary jet on a main jet will only result in a change of direction of the jet if the secondary jet has an axis of symmetry of revolution, said axis being situated in the same plane as the axis representing the direction of the main jet, this plane representing the plane in which the resulting jet is traveling. If these two axes do not intersect, but have a distance d (the smallest distance between them) such that there is an interaction of the two jets, then a composition of two movements is made, one relative to the direction of the jet, the other relative to the opening of the jet, the importance of this second movement (zero 5 when d = 0) increasing as the increase of d then disappearing when increasing, the two jets no longer have any interaction. The invention will be better understood with the aid of the following exemplary embodiments, given in a nonlimiting manner, together with the figures which represent: FIG. 1, a schematic diagram of the method according to the invention of controlling a flow by interaction of jets. - Figure 2 a block diagram of a flame regulation of a burner. FIG. 3 is a block diagram of actuators for controlling the direction of a jet and a method of transforming a twin-jet nozzle into a jet with a variable direction jet. - Figure 4, a block diagram of actuators for controlling the opening of a jet. FIG. 5 is a block diagram of a control of the interaction of two jets. - Figure 6, a diagram of a tube burner tube provided with a quarl, and adapted according to the invention. - Figure 7, a diagram of a burner with separate jets. FIG. 8, a curve of the density of the heat flux of a flame as a function of the distance to the injection point, under different incidences. - Figure 9, different embodiments of the control of the opening of a jet. FIG. 10 illustrates the impact of a control parameter on the deflection of the flame and the transfer to the load. - The figurel1, a curve of the opening angle of the jet as a function of the pulse ratio of the jets. FIG. 12, an example of application of the system of the invention to the heating of a load with change of incidence of the flame. - Figure 13, a diagram of use of the invention for heating a load by laterally moving the flame. 5 - Figure 14, an application of the variable opening of a flame to drive the gases of an oven. - Figure 15, a curve illustrating the emission level of a flame according to a control parameter. - Figure 16, an example of protection of the end of a burner by a quarl. - Figure 17, another example of protection of the end of a burner. In Figure 1 is shown a block diagram of the method of controlling a jet according to the invention. The main jet 3 to be controlled coming from the main injector 15 7 interacts with the actuator jet 2 issuing from the secondary injector 4 thus creating a resultant jet 1 of direction and / or of a different width from the jet 3 in the absence of Actuator 2. It should be noted in FIG. 1 that, in accordance with the invention, the actuator jet 2 conveyed by the secondary injector 4 has the shape of a pipe which passes through the material 5, for example a block surrounding the channel 7, the actuator jet 2 opening through the secondary injector 4, preferably substantially perpendicular to the jet 3. The main jet 3 opens here inside the material 5, that is to say before the jet of the main injector 7 is ejected. The interaction between the two jets takes place at a distance L from the front face 6 from which the main jet 3 opens, this distance L being able to vary as indicated above. Of course, even if it proves preferable according to the invention for the actuating jet to act on the main jet before the ejection thereof from the front face 290 of the block of material 5, it is possible to envisage a substantially identical action if the secondary injector 4 was almost at the output of the main jet 3. One can even consider a pipe such as 4 located outside the block of material 5, but very close to it. In other words, (in the case of an oxygen burner using a fuel CXHy) this distance L can vary as a rule preferably between 0 and 20 cm, more preferably 0 and 10 cm (in the direction shown in Figure 1) this channel may also open up to a few centimeters beyond the point where the main jet opens (for example, by a tube such as 34 in Figure 3 opening out beyond 30). To allow the jet actuator to act as effectively as possible on the main jet, it is necessary to inject the actuator jet substantially perpendicular to the direction of the main jet. In practice, to ensure this orthogonality, it will be necessary to provide a pipe 2 of height f and thickness e, with the relation 0.5, preferably 0.5 FIG. 2 represents a block diagram of a method of regulating the performance of a jet of a lance or burner using a jet system 20 according to the invention. The sensors 14, 16 and 17 measure quantities characterizing the products of combustion and the operating conditions of the process and / or the hearth and the burner. These measurements are transmitted using lines 18, 19 and 20 to the controller 15. The latter as a function of instructions given for these characteristic quantities determines the operating parameters of the actuators 11 so as to maintain the characteristic quantities at their values of These instructions are set and transmitted by means of line 21 to the actuator control members 11. FIG. 3 shows an actuator block diagram for control of the direction of a jet. FIG. 3a is a front view of a jet 30 comprising four actuating jets 31, 32, 33 and 34 respectively arranged for example at 90 from each other and coming in incidence perpendicular to the direction of the main jet 30. If in the absence of an actuator jet, the main jet coming from 30 flows perpendicularly to the plane of FIG. 3a, the injection of a jet into the injector 33 allows a deflection of the main jet coming from 30, towards the 3a (in the direction of 31), ie in the same direction as the direction of flow of the jet 33 (and the same direction) .If simultaneously, the jet 34 is actuated, according to the amounts of relative movement of the jets 33 and 34, it is possible to obtain a jet deviated in a direction (projected in the plane of FIG. 3a) which can vary continuously between the directions of the jets 33 and 34 (towards the right and downwards on Figure 3a). In Figure 3b is shown a side view of the assembly of Figure 3a. Actuator jets 31 and 33 have not been shown. FIG. 3c shows an alternative embodiment similar to FIG. 3b, with, however, an embodiment in which two parallel channels 38 and 43 are limited (seen in section) by the walls 39, 40 and 41, respectively. end of which is reported a pellet 42 which allows to orient the jet actuator of the pipe 43 perpendicularly or substantially perpendicular to the main jet in the cavity 38 so as to obtain a resulting jet, for example in the direction indicated by the arrow 44 in the figure. (The direction of the resulting jet 44 will depend on the ratio of the pulses of the main and secondary jets, thus, by varying the pulse of the secondary jet, a variable resultant jet direction can be obtained to scan an entire surface with this jet. Figure 3d is an exploded view of the nozzle 45 on which is fixed the pellet 42 (by means not shown in this figure) on the front face of the nozzle 45 open the channels 38 and 43 of fluids. this front face comes to apply the pellet 42 in the form here of a hollow lateral cylindrical portion 50 which will come to bear on the end of the nozzle 45, while the opening 46 in the pellet is positioned there where the channel 38 opens out. FIG. 3e shows the bottom (inside) of this pellet 42, the inner face 49 of which has a cavity 47 in which the fluid coming from the channel 43 will divide and come to meet substantially perpendicularly. The resulting stream 44 (FIG. 3c) will thus be deflected downwards (with respect to the drawings of this figure) through the slot 48 thus created above 46, the fluid coming from the channel 38. Figure 4 is an exemplary embodiment of an actuator jet scheme for controlling the opening of a resultant jet. In Figure 4a which is a longitudinal sectional view of an injection device, the main jet 55 (which flows from left to right in the figure) meets the actuator jets (shown in Figure 4b which is a front view along the axis AA 20 of Figure 4a, 51, 52, 53 and 54, which impact the main jet 55 tangentially allowing the pulses of these different jets to open more or less the main jet 55. This opening effect is essentially due to the fact that the actuator jets and the main jet have axes that do not intersect, although the jets have physical interaction with each other, which causes the main jet to rotate on it. Fig. 5 is a schematic diagram of a method for controlling bijets Fig. 5 schematically depicts how to control the interaction between two main streams by the action of secondary jets thereon. possible application is l interaction of a fuel jet and an oxidant jet in a flame to modify the characteristics of this flame. FIG. 5a shows a jet of fuel 61 surmounted by an oxidant jet 62, in the situation where none of the jets is controlled. Figure 5b shows these same jets but in a situation where they are controlled or deflected in opposition (jets 5 convergent). This jet 60 is deflected downwards by the jet actuator 62 while the jet 61 is deflected upwards by the jet actuator 63, directed from bottom to top (unlike 61). FIG. 5c shows these same jets in a situation where the jets are controlled or deflected in the same direction (upwards in the figure): the actuator jets 63 and 65 act from bottom to top respectively on the main jets 61 and 60 resulting in resultant jets both directed upwards. These three examples make it possible to obtain very different directional and morphological flames (length, flattening, etc.). The flame of the resulting jet 64 will be very wide in the median horizontal plane of the injectors, while the flame of the resulting jet 67 will be strongly deflected upwards. FIG. 6 represents an exemplary embodiment of the invention in a tube-in-tube burner (as for example described in US-A-5772427 and US-A-5620316 in the name of the Applicant and marketed by the Applicant) under the trade name ALGLASS. In the figure, the opening block 70 has a cavity 71 into which the bi-tube burner 73-74 opens. In the opening (block) 70 of the burner are drilled a plurality of pipe 75-76 opening respectively through the pipes 77 and 78 substantially perpendicular to the axis of symmetry X - X of the burner 72 at a distance L of the face before 79 of the quarl (70). The burner proper is constituted schematically of a fuel injection tube 74 (preferably), surrounded by a concentric tube 73 in which the oxidant is injected, tube 73 which is fixed in the opening 2903478 19 80 in the quarl 70 (upstream of the quarl in the direction of flow of the fluids), the two fluids mixing in the chamber 71 located downstream of the quarl. In this exemplary embodiment, the actuators on the flame have previously been subjected to a mixture of the oxidants and fuels injected for example into the tubes 73 and 74 coaxially, the flame thus formed being oriented by the action at least one actuator 76, 77 and / or 75, 78. The number of these injection pipes of an actuating jet must be at least preferably equal to 1, in a radial arrangement so as to be able to control the direction flame and / or its opening in the desired direction (symmetry of revolution). Figure 7 relates to the application of invention in a burner said injections 15 separate the different fluids. The separate injection burner 101 has an upper row of oxygen injectors 112 in the form of jets and injectors of natural gas (fuel) 125 in the form of jets, all of the injectors being in the refractory mass. 121 (Figure 7C). The usually metallic portion 102 of the burner 101 is situated on the right-hand part of FIG. 7A and is extended by the oxygen gas injection tubes 107 and 109, on the one hand, and natural gas injection tubes 207 and 209, on the other hand. on the other hand on the left of FIG. 7A. In this figure, there are provided two independent oxygen supplies (or any oxidizer) 104 and 106 respectively supplying the boxes 103 and 105 respectively connected to the tubes 109 and 107, the oxygen flowing through the tubes 110 and 108. 2903478 The end 111 of the tubes is enlarged in FIG. 7B, with the aid of which is explained the interaction of the main jets 108 and the actuator 110. At the end of the tubes 107 and 109 is disposed a channel 127 extending the channel 110 flow of the actuator jet. The wall 109 is extended by the walls 113, 5 inclined upwards, 114, horizontal and 115 vertical (in the figure), while a central volume 126 allows delimiting a channel 127 first inclined upwards, horizontal then vertical (that is to say 90 relative to the gaseous flow channel 108 and opening therein through the opening 120). The vertical part of the channel 127 has a height L, defined above, making it possible to check the orthogonality of the jets 110 and 108 at the level of 120 (of course, if an angle of intersection of the jets other than 90, the channel 127 will have the desired inclination and its length f remaining within the limits provided above). The metal part of the burner ends with a wall 123, vertical in the present case, bordering the channel 127, metal part exposed to the thermal radiation of the fireplace in use. To ensure the longevity of this end of the injection tubes, it will be possible to provide a protective element, for example alumina, resistant to high temperatures, coming, for example, to fit on this metal end to protect it and having a Opening equal to the opening 112 (Figure 7c). The fuel supply system 204, 206, 203, 205 is similar to the oxidizer feed system described above with a main channel 207, an actuator channel 209 defining main fuel jets 208 and fuel actuators 210. , all housed in a cylindrical opening 222 of the opening 221 (similar to 122 for the oxidant). The ends 124 and 125 are similar to 123 and 112. The same fuel actuator jet injection system is provided at the end of 207 and 209 as shown in FIG. 7B, sized according to the characteristics of the fuel. In general, however, it will be preferred to provide only one jet injector jet on the fluid having the highest impulse (generally the oxidant 2903478 21 in the case of a burner), the jet thus deflected causing it - even the deviation of the other jet outside the burner. In such a case of course, the highest pulse jet (or row of jets) will generally be disposed above the lower impulse jet, so that without the action of the jet actuator 5 on the jet of jet. the highest impulse, the burner delivers a flame oriented generally horizontally, whereas when the jet actuator (coming to act up and down on the main jet of higher momentum) acts on the main jet, it is directed, as explained above, downwards (progressively, according to the ratio of the pulses) and carries with it the second lower impulse jet (here the fuel) forming a flame which can thus pass from a position horizontal at an inclined position towards the load to be heated, located under the flame of the burner. By adding an actuator jet on either side of the main jet at 90 (or any other angle between 0 and 180) of said actuator jet illustrated in FIG. 7a, (ie on a horizontal at 123 on Figure 7c, perpendicular to AA) this then allows to move the flame on the load to be heated from left to right or right to left, thus covering substantially the entire surface to be heated. According to the invention, the actuator jet makes with the main jet an angle which is greater than zero. For reasons of space, the two channels leading these jets are fed most often by a co-axial feed system (parallel channels - see Figure 7). Also to reorient the secondary flow at the interaction zone of the two flows, according to a variant of the invention, it is possible to fix at the end of a parallel channel injector,

a

  end piece, hereinafter referred to as an injection pellet and whose function is to transform the direction of the secondary jet initially parallel to the main jet, into a secondary jet 30 impinging on the main jet, ie having a direction of preferably perpendicular to the main jet. (We can of course realize this set in one piece).

The sizing of this injection pellet is conditioned by the reorientation of the secondary flow.

In practice, the ratio = must be greater than 0.5, preferably between 0.5 and 5. However, the use of these actuators for very high temperature processes (T> 1000 C) can lead to overheating and degradation of the injection pellet.

Also in order to overcome this type of problem, it will be sought in the sizing of the injection pellet to reduce the front surface of the injector subjected to radiation in the enclosure at high temperature. For this, we will try to reduce the ratio =. In the situation where this first measurement is insufficient, one of the two solutions will be used, which will be described below with reference to FIGS. 16 and 17. The first solution (FIG. 16) consists of placing the injector 500 in a refractory piece 501 (aperture for the burners) whose geometry and the relative position injector / opening will protect the latter from excessive radiation. The position or withdrawal of the injector in the quarl must be sufficient to protect it from radiation but must not limit the directional amplitude of the injected jet. For this, we can change the geometry of the quarl eliminating part of it along the line 160 dashed in Figure 16 according to the angle a.

Preferably, the ratio d will be in the range 0.3 to 3, while the angle α will be in the range [0, 60]. The second solution is to bring a sleeve type refractory piece 30 directly on the nose of the injector as shown in Figure 17. This solution makes it possible to overcome the presence of a pupil with complex geometry. The dimensions of the sleeve are such that it does not limit the directional amplitude of the injector. This means in particular that the thickness f of the sleeve is small (less than the diameter of the main jet) or that the material used to produce this sleeve has a very low thermal conductivity. For example, alumina will be chosen. Figure 8 shows three heat flux profiles transferred by a flame to a charge according to the angle of incidence of the flame on the charge as a function of the distance to the injection point of the flame reactants. A very large increase in the heat flux transferred to the load is observed with the increase in the incidence of the flame. For a zero incidence (a = 0 ù see Figure 12), the heat flow is substantially constant over the entire length of the flame; for an incidence of 15, the transferred flux increases very rapidly, then a little less rapidly from the point A, whereas for a flame incidence of 30, the transferred flux increases extremely rapidly up to the point B, then less rapidly substantially to point A, from which the transfer decreases.

Figure 9 shows the opening angle of the jet as a function of the ratio of the flow of the actuator jet to the flow rate of the main jet. FIG. 9a shows two curves C1 and C2 respectively representing the opening angle of the jet as a function of the ratio of the jet flow rates actuator / main jet for a configuration CONF1 in which the actuator jets are perpendicular to the main jet and open at a distance h from the output end of the resulting jet and a curve C2 corresponding to a configuration identical to CONF1, but with a distance of 2 h instead of h between the place where the auxiliary jets open in the main pipe and The output end of the resulting jet.

These two curves show that the opening of the resulting jet is greater when the impact between the actuator jets and the main jet is closer to the end where the resulting jet opens.

FIG. 9b also illustrates the variations in the angle of aperture of the resulting jet as a function of the ratio of the flow rates of the actuator and main jets: the curve C3 corresponds to the configuration CONF3 with actuator jets impacting the main jet at 90 °, a distance 2 h from the end (similar to CONF2), while the curve C4 corresponds to the CONF4 configuration identical to CONF3, with the exception of the angle of incidence of the actuator jets which is 45 relative to the axis of the main jet (angle a). Note that when the actuator jets are perpendicular to the main jet (CONF3), we obtain, all things being equal, a larger jet opening than when the angle of incidence has actuator jets is lower (here 45) 15 (CONF4). Figure 10a shows the deflection angle (in degrees) as a function of the ratio of the actuator jet flow rate and the main jet flow rate, expressed as a percentage. FIG. 10a shows four curves, all else being equal, for which the flow rate of the main jet is respectively 200 Um, 150 Umn, 100 Umn and 50 Umn. Note that these four curves are almost identical, which shows that the deviation of the main jet is not a function of flow.

FIG. 10b shows the heat transfer to a load: a heat flux delivered by a burner according to the invention, in which the ratio of the flow of the actuator jets to the flow rate of the main jet (also represented here as a percentage of main jet flow), for both the fuel jet and the oxidizer jet (separate injection burner). Each jet initially injected parallel to the load is progressively deflected towards the load, which increases the heat transfer to the load.

Figure 11 shows a curve of the jet opening angle as a function of the jets pulse ratio. This curve reports all the experimental data obtained for controlling the opening of a jet. The measured aperture angle is plotted against the physical parameter J which is the ratio of the specific pulses of the actuator jets and the main jet. This ratio is written as the product of the ratio of the densities (main fluid actuator fluid) and the ratio of the square of the speed of the actuator jets and the square of the velocity of the main jet). The main fluid is the same for all the experiments, while different fluids have been used for the actuators. These fluids differ mainly in their density (from the density of the largest to the lowest: CO2, Air, Air Helium mixture). It is observed that all the experimental points (whatever the flow rates and the fluids used) are aligned on a straight line. This shows that the physical parameter controlling the opening of the jet is the ratio of the specific pulses defined above. The invention will hereinafter be illustrated in the case of a burner used to heat any filler which may be a metal filler or any other filler which has to be melted and / or brought to a high temperature and then maintained at that temperature. for example a charge of ferrous or non-ferrous metal, glass, cement or, on the contrary, a charge which must be dried from a liquid bath.

Many other applications are possible: for example, the invention can be used on an injection lance of a subsonic and / or supersonic jet, or an oxygen injection lance for refining molten metal. , for example for the injection of subsonic and / or supersonic oxygen into the converter, for example to replace a supersonic multibus nozzle, by at least one single lance whose jet is actuated by one or more actuator jets (or a group of Parallel lances with actuators 2903478 26 to diverge if desired the jets (oxygen, nitrogen, argon or other gas or liquid) .The resulting jet can thus be rotated successively about the axis of the main jet (by the successive action of actuator jets regularly distributed around the periphery of the main jet) and having a sequential injection of subsonic and / or supersonic oxygen into the molten metal bath. use the invention on a tool for treating steel in an electric arc furnace, for example as follows: this type of tool generally comprises a flame (usually subsonic) which can heat the metal, melt it , especially at the beginning of a merger. This flame, as explained in the present application, may be of variable direction by equipping each main jet (oxidizer, fuel, premix) or at least one main jet of an actuating jet which varies its direction and / or its opening, so as to be able to move this flame on the load without requiring heavy mechanical means that change the direction of the burner body. In the center of the tool is generally provided a supersonic speed injection channel (equipped with a Laval nozzle) of gas such as oxygen, nitrogen, etc. This channel can itself be equipped with an auxiliary jet injection channel to vary the direction of the jet (subsonic or supersonic). Actuator jets can also be provided to increase the opening of the main jet, for example when its speed is subsonic. In general, such actuator jets will not be actuated on a supersonic main jet because it is generally attempted to keep the jet opening angle as low as possible in this case, in order to increase the penetration. of this supersonic jet.

In certain operating phases, a central jet (for example oxygen, nitrogen, etc.) is used at supersonic velocity surrounded by a flame in order to keep it as long as possible a speed close to its initial velocity at 30.degree. the outlet of the nozzle (converge / diverge). Depending on the process steps in the electric furnace, the flame may have a greater or lesser opening (that is to say covering the supersonic jet over a greater or lesser length). Finally, these tools are also provided with sprayed coal injection lances, generally injected with vector gas into a lance. By providing this lance with an injection pipe of a secondary jet, for example a gas identical to the propellant of pulverized coal, it will be possible to vary the direction (also the opening of the jet as for any fluid) of the pulverized coal jet (or pulverized fuel oil) in order to promote a rapid encounter of the jet of fuel sprayed with the flame or, on the contrary, to keep the jet from the flame (or the supersonic jet). The invention can also be applied in food or industrial cryogenic appliances in which jets of cryogenic liquid (for example liquid nitrogen) are injected, each jet being able to use the invention and the use of one or more actuator jets, sweeping a surface (for example, watering an entire surface of products to be frozen by means of a single variable jet nozzle (direction of form)) etc. The method and technology of the present invention can be used for the injection of, for example, nitrogen in order to inert certain reactors or processes. Indeed, a combination of injectors steering or rotational effect (jet opening) variables can homogenize more quickly the atmosphere of a reactor, for example, by increasing its entrainment in the jets of inert gas, favoring the supply of nitrogen to sensitive areas through directional effects.

The invention can also be applied to the filling of pressurized gas cylinders: the use of composite materials for storage under pressure, for example of hydrogen, in low weight tanks, limits the filling rate by reason for risk of hot spots.

The flow inside the bottle is organized in a jet along the axis of the bottle with a trigger at the inlet of the bottle, then a downstream zone (bottom of the bottle) where the gases slow down and are compressed. (Thus heat up) and two recirculation zones on each side where the hot gases 10 are driven along the walls before being driven into the central jet. The use of a variable opening injection during the filling of the bottle to reverse the latter situation. Indeed, the injection of a jet with a very large rotational effect makes it possible to generate a flow inside the bottle where the cold gases cooled by the expansion at the bottle inlet 15 will follow the walls of the bottle before be compressed when they arrive at the bottom of the bottle and return to the center of the latter along the axis of the latter. The alternation of these two situations during filling makes it possible to limit the temperature of the bottle and to remain in a temperature range without risk, including for high filling speeds.

Another application of the invention is gaseous quenching: the directional capacity of the injectors according to the invention makes it possible to homogenize the temperature in parts of complex shape and of high thermal resistance. The following examples provide a better understanding of how the invention can be used. The following examples relate to the control of the heat transfer of a burner using the invention to a charge for example metal in a process of melting a load, for example a metal charge (which may comprise parts solid and / or liquid.

An aluminum smelting furnace is generally provided with one or more burners on one or more of the sidewalls surrounding the furnace smelter, disposed above the waterline of the metal when the latter is completely melted (liquid). The axis of the flame, when it is horizontal, is located at a height of 10 and 100 cm from this waterline, preferably between 40 and 80 cm. • Example 1: case of solid material in the oven: In this example, injectors according to the invention are used so that the incidence of flame is variable. (Incidence is defined as the angle of the flame to the horizontal). When the incidence is zero, the flame is horizontal and parallel to the surface. When the incidence is non-zero, the flame is inclined below the horizontal and directed towards the bottom of the melting basin 15 of the furnace. Each jet of fluid is injected into the chamber of the furnace by means of an injector according to the invention, but this type of injector can be used only for the fluid (oxidant or fuel) of higher impulse when this It can interact with the one of less impulse so as to obtain the desired deflection of the flame, typically the oxidant in the case of a gas / air burner, or oxygen / gaseous fuel. In the first part of the aluminum melting cycle, when the metal is predominantly present in the solid state, the flame is adjusted so that it has a non-zero incidence (flame axis between 5 and 75, preferably between 25 and 45). This adjustment considerably improves the thermal transfer of the burner and thus reduces the duration of the melting (as explained using Figure 10).

When most of the solid metal blocks are melted, the flame is adjusted to have a zero angle of incidence. The flame is therefore parallel to the waterline of the liquid metal. This setting makes it possible to continue transferring energy to the charge and to complete the melting of the metal or to refine it by limiting the heating of the already molten metal and consequently its oxidation by the flame or the products of combustion. .

Between the extreme positions of the flame described above (free incidence and zero incidence), it is also possible during the first part of the cycle to adopt an intermediate, static adjustment, where the incidence of the flame is between 5 and 30, preferably between 10 and 25, to achieve a compromise between furnace charge coverage by the flame (projected area of the flame on the bath) and intensity of heat transfer. Figure 12 illustrates the extreme positions of the flame with respect to the load. Figure 12a is a top view of an aluminum smelting furnace 120 equipped with two burners 121, 122 according to the invention producing the flames 123 and 124 respectively, positioned above the metal bath 125. The chimney 126 oven allows the evacuation of smoke produced by the flames. Figs. 12b and 12c show a side view of the same furnace 120 at flame 121. In Fig. 12b, flame 123 is inclined at an angle α to the horizontal, preferably when metal solid 127 is still present on the metal bath 125, while in Figure 12c, the flame is positioned in zero incidence (a = 0). Between the extreme positions of the flame (free incidence and zero incidence), it is also possible during the first part of the cycle to periodically vary the angle of incidence of the flame. For example, the oven operator can manually vary the incidence between 0 to 45 and then return to 0. Preferably, the burner will be driven with a control box for periodically modulating the control ratio of the control. burner, that is to say the ratio of the pulses of the main jet and actuator (s) and therefore the incidence of the flame on the bath. The control signal of the control box may be sinusoidal, triangular, square, etc. with a variable frequency of 0.05 Hz to 100 Hz, preferably triangular at a frequency of 0.1 to 10 Hz. The periodic variation of the position of the Flame makes it possible to homogenize the transfer of heat inside the furnace and thus to melt the solid elements more quickly. Example 2: homogenize the energy transfer to the load: In this example, injectors according to the invention will be used so that the orientation of the flame in a horizontal plane can be modified on demand according to the ratio of each injector is injected into the furnace chamber via an injector according to the invention, but for jets located in the same horizontal plane or horizontal planes few spaced from each other (from one to two jet diameters), it is sufficient to use these injectors only for the peripheral jets when they can interact with the other jets to deviate. The variation of the horizontal orientation can be done in both left and right directions either by equipping each main jet with two lateral actuator jets, or by equipping each main main jet with a single jet actuator, capable of operating the jet. principal in the horizontal direction but of opposite meanings to each other. It is also possible to offset the main injector so that at a zero control ratio, the flame is naturally deflected (to the right or to the left) with respect to the X-axis X 'of the burner in FIG. 13, and then vary the orientation of the flame by gradually increasing the control system control ratio (ie obtain a jet along the X-axis X 'with a non-zero control ratio). The use of one or more variable flame-oriented burners allows the load coverage to be increased by moving the flame in a horizontal plane. (The expression control ratio used above is defined as the ratio of the flow rates of the actuator jet and the main jet, knowing that the pulse of a fluid jet can be controlled simply by the variation of the opening. a valve, increasing the opening of a valve being proportional to the increase in the flow rate of the jet, all things being equal). When the control ratios of the burner (s) are zero, the orientation of the flame is located in the natural axis of the burner and the flame covers a portion of the load. When one of the control ratios is non-zero, the position of the flame is deflected and the flame covers another portion of the load. Fig. 13 illustrates an example of horizontal displacement of a flame over a load; each main jet 130, 132 (oxidizer or fuel) is provided with an actuator jet 131, 133; in FIG. 13a, the control ratio CR of the jet 130 is zero, ie no fluid is injected into the channel 131; the control ratio CR of the jet 132 is on the other hand positive, which means that since 133 acts from bottom to top in FIG. 13a, the actuator jet 133 deflects the main jet 132 upwards in FIG. is to the left with respect to the X-axis X 'of the burner. In FIG. 13b, the control ratios of the two main jets 130 and 132 being zero, (CR = 0), there are no actuator jets in action and the flame propagates along the axis X - X ' .

In FIG. 13c, contrary to FIG. 13a, the control ratio CR of the jet 130 and the jet is positive, which causes the flame to be shifted downwards in the figure (to the right in a view from above). , the main jet 132 and the actuator jet 133 having a zero control ratio (no jet 133).

As explained in Example 1, the furnace operator can vary manually, periodically or not the control ratios to change the position of the flame. The control ratios can also be adjusted using a control box to periodically modulate the burner control ratio. Thus, each burner can cover a larger portion of the load promoting the homogeneity of the heat transfer and making it possible to limit the possible formation of hot spots if refractory materials are in the bath (for example residues based on alumina, recycled or in course of formation by oxidation of the metal being melted), and generally to promote heat transfer to accelerate the constant power melting process, or to reduce energy consumption at constant melting time. Example 3: Incidentally variable flame on the load which sweeps the load laterally. Example 4 Closed Loop Control This embodiment of the invention makes it possible to control the movement of the flame both horizontally and vertically as a function, for example, of various operating parameters of the oven, given by different types of sensors. installed on the oven, including heat flow sensors, temperature, or possibly chemical composition 30 (for example TDL type laser diode). 2903478 34 - A regulation loop whose sensor is a measuring device making it possible to obtain an image of the thermal transfer to the charge or of the oxidation of the aluminum bath, this information making it possible to reduce or increase the transfer to the load by acting on the flow of the actuator jet, 5 as explained above. - A control loop of the flame position based on the measurement of the bath temperature, when at least a portion of the bath is present in the liquid state. As long as the bath temperature is below a Tc value of between 650 and 750 C, for example for aluminum, the flame must remain in non-zero incidence on the bath to maximize the heat transfer. When approaching the Tc value, the flame is progressively raised away from the bath, especially as the target value is reached, in order to limit the risks of oxidation of the charge. The incidence of the flame is then controlled to maintain the temperature at its target value. A loop for regulating the position of the flame based on the measurement of the heat flow This heat flow can possibly be evaluated by means of a temperature difference read between two thermocouples immersed in the bath at two different depths but on the same generator perpendicular to the hearth of the furnace. The heat flow can also be deduced from the heat transfer calculated through the hearth of the furnace, always by measuring the difference in temperature within it. Given the greater resistivity of the hearth, made of refractory materials, it is easier to obtain a significant temperature gradient. The heat flow can also be monitored by means of a flow meter disposed for example in the vault of the melting chamber. Indeed, all other things being equal, any decrease in the flux perceived by the vault and observed by the flux meter will at least partially correspond to an increase in the heat flux transmitted to the load. the absolute value of the heat flux transmitted to the load (or losses to the walls) than to the temporal evolution of the corresponding signal).

The melting of the charge will begin with a flame in sharp incidence on the charge, this incidence being maintained as long as the flux transmitted to the load will remain high. As soon as this flow decreases, indicating an increase in the temperature of the charge and the reduction of its heat absorption capacity, the flame is progressively raised away from the bath, in order to limit the risks of oxidation or overheating of the charge. A loop for regulating the position of the flame, based on the measurement of the composition of the fumes at the outlet of the furnace or inside the furnace, for example before the furnace flue collector, above the bath; between the incident flame and the aluminum bath, etc ... for the detection of one or more species revealing the oxidation of the aluminum bath such as CO: a. The composition of the fumes can be measured in a manner known per se by extraction and analysis (conventional analyzers, TDL or other) or in-situ by absorption (laser diode or other) or electrochemical probe. b. The melting begins with a flame in blunt incidence on the charge, and this incidence is maintained as long as the tracer (s) of the oxidation of the charge are stable and in a small amount. As soon as the concentration of the tracer of the oxidation increases, the flame is progressively raised to remove it from the bath, in order to limit the concentration of the tracer (s), and thus the oxidation of the charge, by acting on the main jet via the actuator jet as explained above. 2903478 36 c. In addition, the position of the flame can be set to reach a setpoint and then maintain a precise setpoint concentration oxidation tracer. It is indeed possible to set a concentration threshold that must not be exceeded and to adjust continuously the incidence of the flame to reach it. It should be noted in all cases that when the load is at least partly composed of cold solid, it can direct the flame positively impacting the load since as the temperatures remain modest, for example less than 600 C for 1 aluminum oxidation rate remains low. When the charge has become essentially liquid, the regulation used becomes important to avoid the rise in temperature of the metal and the oxidation thereof. For an application of the invention to the heating of a material other than aluminum, for example to heat a bath of glass, etc., the same principles of regulation apply, for temperatures and criteria which are different from one material to another, but are in themselves well known to those skilled in the art. All primary techniques for reducing nitrogen oxide emissions from burners or industrial fireplaces utilize the local properties of fluid or flame flows to limit their formation. In particular they aim to reduce the temperature or the concentrations of the reagents (fuel, oxygen) or the residence time of the reactants in the flame and / or in the products of combustion. One of these techniques is to entrain sufficient flue gases in the reactants or flame to lower temperatures, reagent concentration or reduce residence time. For this purpose the burner is dimensioned so as to obtain fuel jets and / or oxidant at high speed (high pulse) and sufficiently distant to obtain the maximum rate of entrainment or recirculation of flue gases compatible with good stabilization of the flame. The stabilization limit is detected at the occurrence of unburnt in combustion products such as carbon monoxide for hydrocarbons. Under certain conditions it is possible to obtain a flameless combustion regime that is particularly favorable to the reduction of emissions.

The limitation of this technique and the combustion technologies that utilize it is that the rate of flue gas entrainment is determined by the burner dimensions and operating conditions. As a result, the performance in terms of emissions can deteriorate very significantly as soon as one deviates from these conditions, but also when fuel is changed, or when the flows specific to the furnace or the furnace contribute significantly. to the properties of the flames. The invention makes it possible to adapt in operation the properties of the flames and in particular the burnt gas recirculation rate, which makes it possible to minimize the emissions of pollutants in all circumstances and ultimately to optimize the performance of the burners. • Example 5: premix burner consisting of an injector placed in a fireplace.

Actuator jets as described hereinbefore are used to change in operation the opening angle of the main fluid jet (or multiple jets). In this case, the main jet is a gaseous premix of fuel and oxidizer. The opening of the jet measures the level of entrainment of the ambient medium by the latter, it can be measured by the angle between the axis of the jet and the straight tangent to the boundary between the jet and the ambient environment. (This boundary can be defined as the place in the jet where the concentration of the injected fluid becomes zero). The opening of the jet is controlled by the ratio of the jet flow of the actuator jet to the total flow rate of the resulting jet. When this control ratio is zero, a transmission level N1 is measured (FIG. 15). This control report is in fact the ratio of the pulses of the jets as explained above.

The control parameter is then increased so as to increase the entrainment of burnt gases in the jet and thus dilute the injected fuel mixture. This dilution will lead to, on the one hand, reducing the temperature and, on the other hand, the concentration of the reagents in the flame. NOx emissions will therefore decrease to N2 (Figure 15). If the value of the control parameter is further increased, the temperature and the concentrations of the reactants become too low to ensure a good stabilization of the flame: unburnt appear in the combustion products.

The emissions of nitrogen oxides are then at a level N3 and the emissions of unburnt at a level 13 too high. The control parameter is then reduced until the optimal level of NO and IO emissions (intersection of the NOx and unburned curves in Figure 15) is reached. This optimum can be obtained manually (passive control) or preferably by an active control device. This device integrates sensors for the measurement of emissions of nitrogen oxides and unburnt, an automat using the control logic explained above and the control devices of the flows of the main jet and the jet (s) actuator (s) at least one injector. The controller will determine the value of the control parameter that minimizes emissions of nitrogen oxides and unburnt. The active control becomes indispensable as soon as the number of parameters to be optimized is greater than or equal to two. For example one can at the same time want to minimize pollutant emissions by increasing the rate of dilution of the flame by the flue gases and maximize the transfer to the load by inclination of the flame to the load. Example 6: Non-premixed Combustion Burner If the combustion technology is of the non-premixed type then the control can be carried out indifferently on the fuel, the oxidant or both in a manner similar to the Example 5 If necessary, the effects of opening (entrainment of the ambient medium) and deflection of the jets (diverging jet of fuel and oxidant) will be combined, and in particular to increase the impact of the dilution of the flame. and maximize the reduction of emissions. For this, various possible configurations are described below: 5 - First configuration: * The deflection and rotation functions of the main jet are provided by separate modules, uni-functional. * The injection device has only one main jet.

In this case, the rotation function (see FIG. 4 for example) must preferably be installed upstream of the direction function (FIG. 1 for example) (in the direction of flow of the main jet) because of the constraint related to the directional function (distance between the output section of the main injector and the interaction section of the secondary jet or jets with the main jet). However, the other 15 case in which the deflection function is installed upstream of the rotation function is possible provided of course to respect the distance constraint recalled previously. - Second configuration: * Deflection and rotation functions are not provided by separate modules. * The injection device has only one main jet.

In this case, by working on the position of the interaction surface of the actuator jet (s), and their respective direction as indicated in the description of the invention, the effects of rotation and direction can be combined. The two limit cases correspond on one side to an injection of the secondary fluid or fluids, normal to the surface of the main fluid, thereby causing directional effects, on the other, to a tangential injection then resulting in mainly rotational effects. . 2903478 - Third configuration: * The injection device has several main jets. In this case, the two preceding options are combined, taking into account, for example, considerations of size or pressure loss already described above. Numerous embodiments of the invention are possible while remaining in the spirit and the basic principle of the invention, according to which a main jet, in a first pipe (for example a pipe which brings this main fluid) encountering a secondary jet, flowing in a second pipe (for example a pipe), preferably about 90 from the first pipe, the second jet coming, by its available momentum, deflect the main jet (the main and secondary jets forming a resultant jet which has neither the direction of the main jet nor the direction of the secondary jet), this deflection movement being more or less accompanied by a movement of opening of the jet, according to the respective locations of the jets at the the impact, (according to the value of d as defined above) knowing that the secondary jet is generally always a jet of smaller section than the main jet, while preferably the two jets are from the same gas source (same gas, same pressure, same temperature).

Claims (3)

claims   1 - Method for heating a charge with a flame generated by a lance and / or a burner, characterized in that in a first phase, the flame is directed towards the charge and in that a second phase, the flame is directed substantially parallel to the load. 2 - Process according to claim 1, characterized in that the lance and / or the burner are fixed. 3. Process according to claim 1 or 2, characterized in that, during the first phase, the injection angle of the flame is between about 90 and 5 and in that during the second phase the injection angle the flame is between about 5 and 0. 4. Process according to one of the preceding claims, characterized in that the injection angle of the flame during the first phase is between 5 and 75, preferably 25 and 45. 5. Process according to one of the preceding claims, characterized in that the flame is direction and / or variable opening. 6. Process according to one of the preceding claims, characterized in that the flame is created by at least one jet resulting from direction and / or variable opening, said jet resulting from the interaction between at least one jet of fluid. main and at least one secondary fluid jet. 7. Process according to the preceding claim, characterized in that the ratio of the flow rates of at least one main jet and at least one secondary jet which interact with each other is varied. Method according to one of the preceding claims, characterized in that the change of direction and / or opening of the flame results from the only interaction of at least one main jet and at least one secondary jet. . 5